Highlighting lines in code listings

README

Compiling it with:

latexmk -pdf main.tex

hello.c

/* hello.c -- The most famous program of them all ..
 */

#include <stdio.h>

int main(void) {
  printf("Hello World!\n");
  // return 0;
}

main.tex

\documentclass [11pt,oneside,onecolumn]{article}

\usepackage{my}

\begin{document}

\code[4]{hello.c}

\end{document}

my.sty

\usepackage{listings}
\usepackage{tikz}
\usepackage{xifthen}

\lstset{
  numbers=left,
  basicstyle=\footnotesize,
  aboveskip=0pt,
  belowskip=0pt,
  showlines = true
}

\lstdefinestyle{highlight}{
  backgroundcolor=\color{orange}
}

\newcounter{linefrom}
\newcounter{lineto}

\def\code{\@ifnextchar[{\@with}{\@without}}
\def\@with[#1]#2{
  \setcounter{linefrom}{1}
  \setcounter{lineto}{1}
  \foreach \x in {#1}{
    \ifthenelse{\equal{\x}{\thelinefrom}}{
      \begingroup\edef\y{\endgroup
        \noexpand\lstinputlisting[linerange=\thelinefrom-\thelineto,style=highlight,firstnumber=last]}%
      \y{#2}
      \addtocounter{linefrom}{1}
    }{
      \setcounter{lineto}{\x}
      \addtocounter{lineto}{-1}
      \begingroup\edef\y{\endgroup
        \noexpand\lstinputlisting[linerange=\thelinefrom-\thelineto,firstnumber=last]}%
      \y{#2}
      \addtocounter{lineto}{1}
      \setcounter{linefrom}{\value{lineto}}
      \begingroup\edef\y{\endgroup
        \noexpand\lstinputlisting[linerange=\thelinefrom-\thelineto,style=highlight,firstnumber=last]}%
      \y{#2}
      \addtocounter{linefrom}{1}
    }
  }
  \addtocounter{linefrom}{1}
  \lstinputlisting[firstline=\the\value{linefrom},firstnumber=last]{
    #2
  }
}
\def\@without#1{
  \lstinputlisting[]{
    #1
  }
}